Poly porous carbons

When [W(CN)s] " was coimmobilized with BOD and poly(L-lysine) on carbon felt sheet of 1-mm thickness on an RDE, a current density of 17 mA/ cm was observed at 0.4 V and 4000 rpm in oxygen-saturated phosphate buffer, pH 7. The authors partially attribute the high current density to convective penetration of the oxygen-saturated solution within the porous carbon paper electrode. This assertion is justified by calculation of an effective electrode area based on the Levich equation that exceeds the projected area of the experimental electrode by 70%. ° This conclusion likely applies to any... 

Dehydrochlorination of poly vinylidene chloride and chlorinated polyvinyl chloride was carried out. High chlorine content in the polymers (more than 60%) provides the formation of chlorinated conjugated polymers, polychlorovinylenes. The reactivity of chlorinated polyvinylenes contributes to the sp carbon material formation during heat treatment. Synthesis of porous carbon has been carried out in three stages low-temperature dehydrohalogenation of the polymer precursor by strong bases, carbonization in the inert atmosphere at 400-600°C and activation up to 950°C. 

The resorcinol-formaldehyde polymers have been used to prepare highly porous carbon materials, by controlled pyrolysis in an inert atmosphere [144,154], The microstructure of the carbon is an exact copy of the porous polymer precursor. Poly(methacrylonitrile) (PM AN) PolyHIPE polymers have also been used for this purpose. These monolithic, highly porous carbons are potentially useful in electrochemical applications, particularly re-chargeable batteries and super-capacitors. The RF materials, with their very high surface areas, are particularly attractive for the latter systems. 

Porous carbons with a high surface area are obtained through the defluorination of poly (tetrafluoroethylene) (FIFE) with alkali metals (AMs) [115], The carbons derived from PIPE were found to have a large number of mesopores and to give a high electric double layer capacitance [116,117],... 

Carbon C (electrographite, Acheson graphite) Carbon black-filled polymers, graphite-filled plastics, graphite-felt, glassy carbon (anode only), porous carbon, poly-p-phenylene (synthetic metal)... 

The aromatic polyimides, cited earlier, separate carbon dioxide over methane with a-valves of 150-160. Aromatic polyoxadiazoles have a-valves of 100-2 00.157 The permeability of one aromatic polyimide was improved by two to four orders of magnitude by carbonizing it on porous alumina,158 the final a-valve being 100. In this case, the final actual membrane was probably a porous carbon molecular sieve. Facilitated transport has also been used to increase the separation factor. A porous poly(vinylidene difluoride) membrane with ethanolamine or diethanolamine in the pores gave a separation factor of carbon dioxide over methane of 2000.159 Such a method is less energy-intensive than when an amine is used in the usual solvent method. 

Przepidrski et al. reported the competitive uptake of SO2 and CO2 on the porons carbon materials containing CaO and MgO, prepared by carbonization of poly(ethylene terephthalate) mixed with a natural dolomite. The as-prepared porous carbon was examined as a sorbent for simultaneous removal of CO2 and SO2 from air in dry conditions and in a presence of humidity, at temperatures ranging from 20 to 70 °C. The attained results clearly confirmed the crncial effect of water on the amounts of gases removed from air streams and the removal mechanisms. The... 

To interpret the pore size distribution of porous carbons, an intersecting capillaries model (ICM) is often used to approximate the microstructure of nanoporous carbons. The pores are assumed to be a poly-disperse ensemble of slit pores with smooth graphite walls, which are connected in some way. Despite its simple geometry, this ICM has been used successfiilly to characterize carbon adsorbents and to predict adsorption in these materials and thus will likely remain the dominant approach to characterization by adsorption [1]. 

Integration of a H2 PSA process with an adsorbent membrane can meet this goal [23, 24]. A nano-porous carbon adsorbent membrane called Selective Surface Flow (SSF) membrane which selectively permeates CO2, CO and CH4 from their mixtures with H2 by an adsorption- surface diffusion-desorption transport mechanism may be employed for this purpose. The SSF membrane can produce an enriched H2 gas stream from a H2 PSA waste gas, which can then be recycled as feed to the PSA process for increasing the over-all H2 recovery. The membrane is prepared by controlled carbonization of poly-vinyledene chloride supported on a macro-porous alumina tube. The membrane pore diameters are between 6 -7 A, and its thickness is - 1-2 pm [25]. 

The poly merblends of PI and polyvinylpyrrolidone (PVP) was used as precursor, assuming that the partially intermingled PVP phase in the continuous PI matrix will produce porous carbon structures by the decomposition of PVP during pyrolysis [62], PI was synthesized from benzophenone tetracarboxylic dianhydride (BTDA) and 4,4 -oxydianiline (ODA). Membranes were prepared by casting the polymer dope, either PI or PI/PVP blend, on a glass plate. The east polymer film was im-idized by stepwise heating up to 250°C and then carbonized at either 550 or 700°C. 

For the fabrication of CMS membranes from commercially available relatively inexpensive polymeric material, Centeno and Fuertes chose poly(vinylidene chloride-co-vinyl chloride) (PVDC-co-PVC) copolymer commercially available imder the trade name of Saran [63]. The polymer solution was spin-coated on a finely polished surface of porous carbon support. In some cases the polymer film was preoxidized in air at 150 or 200°C. The carbonization was carried out at either 500 or 1,000°C. 

The matrices of polymers such as poly(vinyl pyrrolidone) (PVP), polysul-fone, poly(trimethylene carbonate) (PTMC), triethylene glycol diacetate-butyl propenoate copolymer [28], and cellulose [29] are different from the mentioned polymers in Sections from 11.1 to 11.5. For example, when porous polysulfone is used as the polymer carrier, the ionic conductivity (3.93 x 10 S/cm at room temperature) and mechanical performance are greatly improved after adding plasticizers. When organic electrolyte is added to PTMC, the uptake ability is greatly improved because its structure is similar to that of the organic electrolyte. Methylcellulose (MC) is prepared easily as a porous polymer membrane, as illustrated in Figure 11.34. It can absorb liquid electrolyte to become a gel polymer electrolyte whose ionic conductivity is 0.2 mS/cm and lithium-ion transference number is 0.29. These results can compare with the commercial separator [29]. 

This review will be organized on the basis of the plastic polymer used as the precursor for porous carbon production. Section 2 will include studies using various thermoplastics as precursors, whereas Sect. 3 will focus more deeply on poly (ethylene terephthalate) (PET) due to its popularity. 

Poly(ethylene terephthalate) (PET) is used for bottles, carpets, and food packaging and is a very common waste polymer. It comprises 11.7% of the municipal waste plastic in Western Europe. Due to the fact that over 90% of all PET is used in packaging (in particular drink bottles because of its gas barrier characteristics) the majority of PET becomes waste within less than a year of production [1]. This plastic is commonly seen in studies attempting to derive porous carbons from plastic wastes due to the relatively higher residue that remains after its pyrolysis. A complete section in the review is allocated to PET due to its relative popularity for AC production. 

---